<!--
Copyright (c) 2011 The Chromium Authors. All rights reserved.
Use of this source code is governed by a BSD-style license that can be
found in the LICENSE file.
 -->
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>WebGL Scissor Test</title>
<link rel="stylesheet" href="../../resources/js-test-style.css"/>
<script src="../../resources/desktop-gl-constants.js" type="text/javascript"></script>
<script src="../../debug/webgl-debug.js"></script>
<script src="../../resources/js-test-pre.js"></script>
<script src="../resources/webgl-test-utils.js"></script>
</head>
<body>
<div id="description"></div>
<div id="console"></div>
<canvas id="canvas" width="2" height="2" style="width: 40px; height: 40px;"> </canvas>
<script>
description("Check if glScissor setting works.");

debug("");
debug("Canvas.getContext");

var wtu = WebGLTestUtils;
var gl = wtu.create3DContext(document.getElementById("canvas"));
if (!gl) {
  testFailed("context does not exist");
} else {
  testPassed("context exists");

  debug("");

  gl.clearColor(0,0,0,0);
  gl.clear(gl.COLOR_BUFFER_BIT);

  // clear a portion of our FBO
  gl.enable(gl.SCISSOR_TEST);
  gl.scissor(0, 0, 1, 1);
  gl.clearColor(0,1,0,1);
  gl.clear(gl.COLOR_BUFFER_BIT);

  var b = new Uint8Array(2 * 2 * 4);
  gl.readPixels(0, 0, 2, 2, gl.RGBA, gl.UNSIGNED_BYTE, b);

  function checkPixel(b, x, y, color) {
    var offset = (y * 2 + x) * 4;
    var match = true;
    for (var c = 0; c < 4; ++c) {
      if (b[offset + c] != color[c] * 255) {
        match = false;
        break;
      }
    }
    assertMsg(match, "pixel at " + x + ", " + y + " is expected value");
  }

  checkPixel(b, 0, 0, [0, 1, 0, 1]);
  checkPixel(b, 1, 0, [0, 0, 0, 0]);
  checkPixel(b, 0, 1, [0, 0, 0, 0]);
  checkPixel(b, 1, 1, [0, 0, 0, 0]);
}

debug("");
successfullyParsed = true;

</script>
<script src="../../resources/js-test-post.js"></script>

</body>
</html>
